I searched the forums and didn't see anything on this so here goes...

I have a 2005 with the factory alarm along with the optional dealer add-on alarm system.

The keyless entry works, locks and unlocks the doors, lights flash, trunk button works.

The panic button works, horn sounds, lights flash, etc.

But the alarm isn't getting armed. I can lock the doors with the FOB, sit in the car, and open the door, no alarm.

Also, there is a light on the dash that used to blink periodically when it was armed, it doesn't anymore.

I took it to the stealership, they couldn't find anything wrong...said the next step was to replace the control unit but
Couldn't give me a straight answer regarding if I would have to pay for it if it didn't fix the issue.

Anyone seen this before and have an idea as to what the problem might be before I play Russian roulette with
The stealership and have them replace the control unit?

 

I would just get an upgraded alarm if it's going to be expensive to fix.

 

I believe there is a different fob for the alarm than the standard keyless entry -
if you are using a fob that worked before, that's obviously not the problem.
Otherwise your best bet is to use a multimeter to check the various connections -
for instance, it may be that the alarm thinks a door is open so it doesn't arm.
Here are the OEM alarm installation instructions, which may help you identify
what's where.